\begin{tikzpicture}
    \tkzDefPoints{0/0/B, 3/0/C, 3/2/A}
    \tkzDefLine[altitude](A,C,B)  \tkzGetPoint{F}

    \tkzDrawPolygon(A,B,C)
    \tkzDrawSegments(C,F)
    \tkzMarkRightAngle[size=0.15](A,C,B)
    \tkzMarkRightAngle[size=0.15](C,F,B)
    \tkzLabelPoints[above](A)
    \tkzLabelPoints[below](B)
    \tkzLabelPoints[left](F)
    \tkzLabelPoints[right](C)
\end{tikzpicture}

